1. Field of the Invention
The present invention relates to a temperature sensor for the tip of a surgical instrument.
2. Description of Related Art
Surgical procedures are sometimes performed with an ultrasonic instrument that emulsifies tissue. For example, cataracteous lenses are typically emulsified by an ultrasonic tip that is inserted to the cornea of a patient. The vibrating tip of the ultrasonic instrument can generate heat that raises the temperature of the eye.
Conventional ultrasonic interocular instruments have a fluid system which removes the debris created by the vibrating tip and provides a coolant for the eye. It has been found that the debris created by the tip may occlude the aspiration/irrigation system of the instrument. The occlusion may interrupt the cooling process of the procedure and cause the cornea temperature to increase to a level which may damage the eye. It would therefore be desirable to have temperature sensor that provides an indication of when the instrument tip has exceeded a threshold level.
The length of an ultrasonic tip and the thermal inertia of the instrument require that a temperature sensor be located on the tip. Conventional wire thermocouples have a relatively slow response time such that the corneal tissue may become damaged before the surgeon is provided with an indication that the threshold temperature has been exceeded. Additionally, thermocouples are relatively bulky and may affect the operation of the instrument. Although infrared (IR) temperature sensors are not intrusive, IR sensors are relatively inaccurate because of the thermal dispersion in aqueous mediums. It would therefore be desirable to provide a non-intrusive, accurate, responsive, temperature sensor for a surgical instrument.